Generally, in such circuit breakers, the first contact and the piston are fixed, the separation of the contacts and compression of the dielectric gas in the compression chamber being effected simply by movement of the second, movable contact.
French patent FR 2 491 675 discloses a cut-out device whose contacts are moved in opposite directions in order to increase the speed of contact separation without increasing the speed of the movable contact. The actuating means are formed by a system of links and connecting rods.
French patent FR 2 320 626 describes a circuit breaker with a movable contact and piston movable by means of rods, the fixed contact being integral with the cylinder forming the blast chamber.
In a circuit breaker with a dielectric gas such as SF.sub.6, high speed of separation of the contacts and a large stroke to withstand the voltage are sought after in order to interrupt capacitive currents. To interrupt short circuit currents and currents due to remote faults, a high blast pressure and a rapid build-up of pressure are required.
The object of the invention is to interrupt these types of current adequately, while using as little energy for operation as possible.